Atom motion of Cu and Co in Cu damascene lines with a CoWP cap

Electromigration of Cu and diffusion of Co in Cu damascene bamboo-like grain structure lines capped with CoWP have been studied for sample temperatures between 350 and 425 °C. Void growth from the Cu line/W via interface was observed. Bulk-like activation energy for electromigration of 2.4±0.2 eV was obtained for these samples suggesting that electromigration damage is greatly diminished for these on-chip Cu interconnections. The solubility and diffusivity of Co in Cu was determined from line resistance measurements of thermally annealed Cu lines which were affected by Co diffusion into the Cu line.